RESEARCH ARTICLE


Elucidating the Pozzolanic Characteristics of Pastes Containing Circulating Fluidized Bed Fly Ash



Kae-Long Lin, Chao-Lung Hwang2, Yu-Min Chang3
1 Department of Environmental Engineering, National Ilan University, No. 1, Sec.1, Shen-Lung Rd., Yilan, 26047, Taiwan, ROC
2 Department of Construction Engineering, National Taiwan University of Science and Technology, Keelung Rd., Sec. 4,Taipei 106, Taiwan, ROC
3 Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei 106, Taiwan, ROC


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Creative Commons License
© 2015 Lin et al;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Environmental Engineering, National Ilan University, No. 1, Sec.1, Shen-Lung Rd., Yilan, 26047, Taiwan, ROC; Tel: +886-3-9357400ext 749; Fax: +886-3-9364277; E-mail: kllin@niu.edu.tw


Abstract

The aim of this study is to investigate the pozzolanic characteristics of circulating fluidized bed fly ash blended cement (CFBFABC) paste containing circulating fluidized bed fly ash (CFBFA). The initial and final setting time of CFBFABC pastes with CFBFA retards with an increasing CFBFA content. CFBFABC pastes containing 10% CFBFA exhibited a compressive strength similar to that of ordinary Portland cement pastes at the ages of 90 days. X-ray diffraction peaks indicated the presence of portlandite, ettringite, and unreacted C3S (32.6°) and C2 (41.9°). The gel/space ratio of the CFBFABC pastes increased with the curing time and decreased as the CFBFA content increased. The gel/space ratio increased with the curing time because of the progress of hydration, which led to some of the pores being filled. At the ages of 90 days, the gel/space ratio of the CFBFABC pastes containing 10% CFBFA increased to approximately 14%, it is possibly the consumption of Ca(OH)2 and the formation of C-S-H in the CFBFABC pastes. The CFBFABC pastes containing 10% CFBFA did not exhibit any major decrease in the gel/space ratio. It exhibited favorable mechanical characteristics that were observed when the mixing ratio of CFBFA was 10%. Furthermore, CFBFA has the potential, as a pozzolanic material, partially to replace ordinary Portland cement.

Keywords: Circulating fluidized bed fly ash, compressive strength, gel/space ratio, hydration, Pozzolanic, setting time.